About Motion Tracking

Motion provides a set of automated tracking behaviors that allow you to do the following:

• Match move elements in movie clips: You can apply tracking data from a background element (such as a billboard) to a composited foreground element (such as a graphic of a logo) so both elements appear to be locked together. This technique is known as match moving.
• Match move animated objects in the Canvas: You can apply the motion data of an animated object to another object in the project. For example, you can attach a smoke particle emitter to an animated spaceship so a rocket exhaust trail follows wherever the spaceship moves.
• Stabilize camera movement in movie clips: You can apply tracking data to remove unwanted camera movement or jitter in a movie or image sequence. For example, you can smooth handheld camera shots.
• Unstabilize movie clips: You can restore movement to a previously stabilized movie. This technique is useful when you stabilize a clip to add a foreground effect but want to restore the original camera movement to the final composite.
• Track the position parameter of a filter: You can apply tracking data to the position parameter of a filter. For example, you can make the center point of a Light Rays filter follow a moving flashlight beam in a movie clip. The tracking data from the flashlight beam is applied to a single parameter of the filter (the Center parameter), rather than to the filter as a whole.
• Track the control points of a shape or mask: You can apply tracking data from reference points in a movie clip to the control points of a shape or mask. For example, you can use this technique to attach a mask to a moving element in a movie clip, isolating that element to apply additional effects to it.

Motion lets you track one or multiple reference features in a clip:

• One-point tracking: Track a single reference pattern (a small area of pixels) in a movie clip to record position data.
• Two-point tracking: Track two reference patterns in a movie clip and use the relationship between the tracked points to record position, scale, and rotation data.
• Four-point tracking: Often referred to as four-corner pinning. Track four reference patterns in a movie clip to record position, scale, and rotation data. The four trackers analyze the relationship between four reference patterns, such as the corners of a picture frame or television monitor. This data is applied to each corner of an image or clip to “pin” the clip so it appears locked in the picture frame or television monitor.
• Multiple-point tracking: Track as many reference patterns in a clip as you like. You can manually add trackers in the Analyze Motion behavior. When you apply a Track Points behavior from the Shape behaviors subcategory to a shape or mask, a tracker is assigned to each shape control point.

Note: Although Motion provides a 3D workspace, tracking in Motion is planar. In other words, tracking does not occur in Z space. For example, if you are analyzing two features in a clip—and that clip is moving in 3D space—you are recording the changes in position, scale, or rotation over time in the clip, but not its actual 3D transformation.

The object tracked is called the background or source element. The object to which the tracking data is applied is called the foreground or destination element.